Our Projects

Snohomish County Surface Water Management (SWM) proposed 29 culverts and 2 water quality facilities for replacement as part of a program to improve fish passage and habitat conditions. Confluence managed the effort to determine applicable U.S Army Corps of Engineers (Corps) regulatory requirements for the proposed projects. Confluence worked with design engineers to assess field […]

Sierra Pacific Industries (SPI) developed industrial land in Frederickson, Washington. Confluence Environmental Company served as the lead consultant for site SEPA; critical areas studies; off-site wetland mitigation design and planning; environmental review; and local, state, and federal environmental permitting for the property. Confluence led the multi-disciplinary team from design of site development through design of […]

King County Wastewater Treatment Division is upgrading the King County sewer system from the North Mercer Island Pump Station to Sweyolocken Pump Station in Bellevue. Phase 1 included a multi-stage alternative analyses process. For this project, Confluence provided technical expertise related to wastewater conveyance and infrastructure work in sensitive habitats such as the Mercer Island […]

Washington State Department of Transportation (WSDOT) is replacing the State Route (SR) 520 bridge. The work is divided into three projects: West Side/Floating Bridge, East Side Transit and HOV, and Pontoon Construction. Confluence’s leadership in implementing the environmental strategy has enabled WSDOT to meet a very aggressive schedule for environmental project delivery on one of […]

Few studies have addressed how and whether off-bottom oyster culture affects species use and abundance, or whether these differences affect the overall food web ecology of the system. Confluence designed and is leading a grant-funded study to research comparative habitat use of estuarine habitats with and without cultch-on-longline gear present. The project addresses the goal […]

The Mid-Barataria Sediment Diversion project is a component of the Coastal Louisiana restoration strategy that proposes to divert sediment-laden water from the Mississippi River to restore natural deltaic processes and increase land area in the Barataria Basin. Over a 50-year time frame, the project would build and maintain 10,000 to 30,000 acres of upland, and […]

Confluence Environmental Company staff have worked with shellfish growers for many years, individually and collectively. Our scientists have provided regulatory compliance and permitting strategies; developed biological assessments, habitat plans, and permitting documents; researched shellfish ecology; and created study designs for a wide range of shellfish aquaculture projects. Confluence’s work with growers at the individual project […]

Confluence Environmental Company evaluated coastal processes along 4 miles of Puget Sound shoreline between Mukilteo and the Port of Everett to select priority sites for beneficial reuse of dredge material through beach nourishment and habitat restoration. Confluence assisted the Snohomish County Public Works Department (County) throughout the process — from site evaluation to selection of […]

Confluence Environmental Company led a team to address fish passage and habitat restoration on Japanese Gulch Creek. The original scope of the project was to improve fish passage in a concrete junction box between upstream and downstream culverts, where streamflow was spread over a concrete apron in a very thin layer that was a severe […]

Confluence Environmental Company staff provided regulatory compliance support, environmental review, permitting, and strategic input integral for the construction of a 2.5-mile, in-lake sewer line segment along the Lake Washington shoreline. The project was particularly challenging because of the sensitive shoreline resources including Endangered Species Act (ESA)-listed species, the technical challenges of maintaining reliable sewer service […]